package com.itheima.web.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DownloadServlet extends HttpServlet {

	/**
		 * Constructor of the object.
		 */
	public DownloadServlet() {
		super();
	}

	/**
		 * Destruction of the servlet. <br>
		 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
		 * The doGet method of the servlet. <br>
		 *
		 * This method is called when a form has its tag value method equals to get.
		 * 
		 * @param request the request send by the client to the server
		 * @param response the response send by the server to the client
		 * @throws ServletException if an error occurred
		 * @throws IOException if an error occurred
		 */
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		response.setContentType("text/html");
		// 使用java图形界面技术绘制一张图片

					int charNum = 4;
					int width = 30 * 4;
					int height = 30;

					// 1. 创建一张内存图片
					BufferedImage bufferedImage = new BufferedImage(width, height,
							BufferedImage.TYPE_INT_RGB);

					// 2.获得绘图对象
					Graphics graphics = bufferedImage.getGraphics();

					// 3、绘制背景颜色
					graphics.setColor(Color.YELLOW);
					graphics.fillRect(0, 0, width, height);

					// 4、绘制图片边框
					graphics.setColor(Color.BLUE);
					graphics.drawRect(0, 0, width - 1, height - 1);

					// 5、输出验证码内容
					graphics.setColor(Color.RED);
					graphics.setFont(new Font("宋体", Font.BOLD, 20));

					// 随机输出4个字符
					Graphics2D graphics2d = (Graphics2D) graphics;
					 String s = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";
					Random random = new Random();
					//session中要用到
					String msg="";
					int x = 5;
					for (int i = 0; i < 4; i++) {
						int index = random.nextInt(32);
						String content = String.valueOf(s.charAt(index));
						msg+=content;
						double theta = random.nextInt(45) * Math.PI / 180;
						//让字体扭曲
			            graphics2d.rotate(theta, x, 18);
						graphics2d.drawString(content, x, 18);
						graphics2d.rotate(-theta, x, 18);
						x += 30;
					}

					// 6、绘制干扰线
					graphics.setColor(Color.GRAY);
					for (int i = 0; i < 5; i++) {
						int x1 = random.nextInt(width);
						int x2 = random.nextInt(width);

						int y1 = random.nextInt(height);
						int y2 = random.nextInt(height);
						graphics.drawLine(x1, y1, x2, y2);
					}

					// 释放资源
					graphics.dispose();

					// 图片输出 ImageIO
					ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
				
	}

	/**
		 * The doPost method of the servlet. <br>
		 *
		 * This method is called when a form has its tag value method equals to post.
		 * 
		 * @param request the request send by the client to the server
		 * @param response the response send by the server to the client
		 * @throws ServletException if an error occurred
		 * @throws IOException if an error occurred
		 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.print("    This is ");
		out.print(this.getClass());
		out.println(", using the POST method");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	/**
		 * Initialization of the servlet. <br>
		 *
		 * @throws ServletException if an error occurs
		 */
	public void init() throws ServletException {
		// Put your code here
	}

}
